THE Australian radio prank is the third major security lapse involving young royals in recent months.

So far, however, Scotland Yard has refused to accept any blame for not taking basic precautions to protect the privacy of the Duke and Duchess of Cambridge and Prince Harry.

In August, pictures of a naked Harry were seen on the internet all over the world after he invited partying girls into his Las Vegas bedroom for a game of strip billiards.

There was criticism that the Prince’s minders should have taken camera phones from the revellers and made them leave them at the door of the suite, but Metropolitan Police Commissioner Bernard Hogan-Howe said officers were right not to intrude.

He told the Home Affairs Select Committee in September: “They have to lead a normal life and we have to strike a balance between intrusion into their lives and keeping them safe. There is a golden line that cannot be crossed, which is the social lives of the principals.”

We have to strike a balance between intrusion into their lives and keeping them safe

Commissioner Bernard Hogan-Howe

Eyebrows were also raised when one of Harry’s bodyguards was photographed in a Jacuzzi with him.

Mr Hogan-Howe said: “There was nothing inappropriate and what appeared in photographs to be wrong was not as appeared.”

In September, pictures of Kate sunbathing topless at Lord Linley’s French holiday home appeared in several magazines and websites around the world and William ordered lawyers to take action in the French courts.

It came as Kate’s protection officer, Emma Probert, who has guarded the Duchess since her engagement to William in 2010, went on maternity leave with her first child. The experienced officer, who carries a lightweight 9mm Glock pistol hidden inside her plain clothes, had been known as Kate’s “right-hand woman”.

Princess Diana’s former bodyguard Ken Wharfe said last night that the incidents would not have happened in his day, and said there had been a “breakdown in protocol” which allowed the Australian DJs to get through to the hospital.

“When I was protecting Diana the first thing we did when we arrived at a hotel or anywhere else was to isolate the switchboard,” he said. “You tell the staff to put any calls through to the detective there.

“The royals never ring in to hospitals on an open line. If anyone needed to speak to Kate they would ring the officer sitting outside her room. All this should have been explained to the hospital staff, but clearly it wasn’t, which is the fault of the police and the hospital.”

A former aide to Princess Margaret, who was often treated at the King Edward VII Hospital, revealed last week how every call was treated with suspicion.

“They went first to the police bodyguard, he would put them through to HRH’s dresser Sandra and she would know instantly who was who. I suspect this is the downside of William and Kate employing hardly any staff.”

Chief Superintendent Dai Davies, former head of royal protection, said the royal couple’s security should be reviewed.

“There comes a time in any organisation when it is sensible to review all protocols and systems.” he said.